Q: Upload file to blob storage - Error with upload That's how I try to upload a photo to blob storage, but every time I try to upload, it gives me a mistake.
It's like it will not let me upload the image to blob storage.
What I want it to do is upload the file and then redirect it to the new name.
public async Task<IActionResult> UploadFileToNewsAsync(IFormFile files, AdminViewModel model)

var name = UrlFriendlySEO.Url(model.NameValue);//make this name SEO friendly here.
var filename = name + png;

CloudStorageAccount storageAccount = new CloudStorageAccount(new Microsoft.WindowsAzure.Storage.Auth.StorageCredentials(Accountname,KeyValue), true);
// Create the blob client.
CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

// Retrieve a reference to a container.
CloudBlobContainer container = blobClient.GetContainerReference(ContainerValue);

CloudBlockBlob blockBlob = container.GetBlockBlobReference(filename);
using (var f = System.IO.File.OpenRead(files.FileName))
{
    await blockBlob.UploadFromStreamAsync(f);
}

Every time I try with the postman, it gives me this mistake.
using (var f = System.IO.File.OpenRead(files.FileName))

My view:
<div class="form-group">
            <div class="col-xs-12">
                @Html.LabelFor(u => u.File)
                <input id="file" name="file" type="file" />
            </div>
        </div>

EIDT Complete:
//ERROR FROM HERE
            CloudStorageAccount storageAccount = new CloudStorageAccount(new Microsoft.WindowsAzure.Storage.Auth.StorageCredentials(Accountname, KeyValue), true);
            // Create the blob client.
            CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

            // Retrieve a reference to a container.
            CloudBlobContainer container = blobClient.GetContainerReference(ContainerValue);

            CloudBlockBlob blockBlob = container.GetBlockBlobReference(name);
            await blockBlob.UploadFromStreamAsync(model.FileToUpload.OpenReadStream());


A: 
Every time I try with the postman, it gives me this mistake.

As Saruman asked, I am not very clear about what mistake you have got.
I test it in my asp.net core and it works well. I think you may not get the files you have upload. 
Please change input name to files as below:
 <input id="file" name="files" type="file" />

You could refer to the detailed code as follow:
In Controller:
public async Task<IActionResult> UploadFileToNewsAsync(IFormFile files, AdminViewModel model)
        {
            var name = UrlFriendlySEO.Url(model.NameValue);//make this name SEO friendly here.
            var filename = name + png;           
            CloudStorageAccount storageAccount = new CloudStorageAccount(new Microsoft.WindowsAzure.Storage.Auth.StorageCredentials(Accountname, KeyValue), true);
            // Create the blob client.
            CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

            // Retrieve a reference to a container.
            CloudBlobContainer container = blobClient.GetContainerReference(ContainerValue);

            CloudBlockBlob blockBlob = container.GetBlockBlobReference(filename);
            using (var f = System.IO.File.OpenRead(files.FileName))
            {
                await blockBlob.UploadFromStreamAsync(f);
            }
            return View();
       }

In View:
@using (Html.BeginForm("UploadFileToNewsAsync", "Home", FormMethod.Post,new { enctype = "multipart/form-data" }))
{
    <div class="form-group">
        <div class="col-xs-12">
            @Html.LabelFor(u => u.File)
            <input id="file" name="files" type="file" />
        </div>
        <input type="submit" />
    </div>
}

